We are witnessing a phase where rapid progress is being made in research and development related to 5G Millimeter wave communication. Institutes and industries are working for realization and implementation of this technology. It is in this backdrop our research work focuses on development of antenna and polarizer component for one of the 5G millimeter wave frequency band (Ka-band). Objectives are to design and develop compact, low loss, wide-bandwidth and commercially viable i.e., low fabrication cost waveguide components for 5G millimeter wave frequencies. The last requirement can be met by utilizing 3D fabrication process and has been used in the current research. This thesis work involves the design and development of 3D printed polarizer and feed horn antenna at millimeter wave frequency. A highly compact circular waveguide based polarizer is designed at Ka-band. The design consists of a pair of radially opposite grooves located on the inner wall of waveguide. An equivalent model based on higher order mode analysis is developed to calculate the cutoff frequency of the modified structure. The cutoff frequency at different operating frequencies are calculated and compared with full wave simulation software HFSS to validate the model. The design is fabricated using direct metal laser sintering process. The fabricated polarizer has a measured 3dB axial ratio bandwidth from 28-34 GHz. The second design is related to 3D printed axial corrugated horn operating over the full Ka-band (26.5-40 GHz). The horn antenna consists of axial corrugations which makes the design very compact. The physical parameters of the corrugation such as step size and width are designed based on higher order mode coupling from the fundamental TE11 to TM11 and TE12 mode. This gives physical insight into the influence of design parameters on the radiation pattern. The designed horn is fabricated using 3D metal printing. Measured radiation patterns show good pattern symmetry and cross-polarization level better than 29 dB is achieved in the principal planes over the frequency band.